Chain for mining machines and the like

ABSTRACT

An endless chain for a mining machine or the like which can be made up to any desired length and width. In one embodiment, the chain can be made to carry cutting tools in any suitable pattern or arrangement and will comprise a plurality of standard link elements and a plurality of standard chain block elements. In another embodiment, the chain can serve as an endless tread for a self-propelled mining machine, in which instance it may be comprised of a plurality of identical, standardized link elements or it may be comprised of a plurality of standard link elements and a plurality of one or more types of modified link elements. In both embodiments, the link elements, or the link and chain block elements, will be joined together by connecting pins of appropriate lengths.

United States Patent Krekeler [54] CHAIN FOR MINING MACHINES AND THE LIKE [72] Inventor: Claude B. Krekeler, Cincinnati, Ohio [73] Assignee: The Cincinnati Mine Machinery Company,

Cincinnati, Ohio [22] Filed: Oct. 30, 1970 [21] Appl.No.: 85,601

[451 July 25, 1972 FORElGN PATENTS OR APPLICATIONS 2l3,746 l2/l968 U.S.S.R. ..299/82 Primary Examiner-Ernest R. Purser Attorney-Melville, Strasser, Foster & Hofiman [57] ABSTRACT An endless chain for a mining machine or the like which can be made up to any desired length and width. In one-embodiment, the chain can be made to carry cutting tools in any suitable pattern or arrangement and will comprise a plurality of standard link elements and a plurality of standard chain block elements. In another embodiment, the chain can serve as an endless tread'for a self-propelled mining machine, in which instance it may be comprised of a plurality of identical, standardized link elements or it may be comprised of a plurality of standard link elements and a plurality of one or more types of modified link elements. In both embodiments, the'link elements, or the link and chain block elements, will be joined together by connecting pins of appropriate lengths.

19 Claims, 12 Drawing Figures PATENTED L I 3.679.265

sum 1 or 3 IN VENTOR S CLAUDE B. KREKELER F I G. 3 BY ym (95 2 and infill ATTORN EYS PATENTEnJuL2s I972 SHEEI 2 [IF 3 FIG.

' FIG. I2

INVENTOR S CLAUDE B. KREKELER PNENTEUJULZS m2 snmaur lNVENTOR/S CHAIN FOR MINING MACHINES AND THE LIKE BACKGROUND OF THE INVENTION 1. Field of the Invention SUMMARY OF'THE INVENTION The invention relates to achain construction for mining "machines and the like. When the chain is adapted to carry .cutting tools, it cancomprise a plurality of connecting links 5 The invention relates to a novel chain construction, and and chm-n blocks f b tantially the same length and width more particularly to chains which may be varied both in length and in width and which may be adapted to carry cutting tools in any desired pattern or arrangement, but which require only aminimum number of standardized parts for their construction.

2. Brief Description of the Prior Art While the chain of the present invention may have many applications, as will be described hereinafter, for purposes of an exemplary showing, the chain will be described in its use. as a trim chain for a non-oscillating drum-type mining machine.

Non-oscillating drum-type mining machines havecome into extensive use. Briefly, such machines generally comprise .a self-propelled vehicle having a centrally located conveyor means for the material being mined. At the forward end' of the.-

. about its axis to produce a cutting action. In usual practice,

the machine is brought to the face of the materialbeing cut and the drum is sumped into the face. at the. top thereof. Thereafter, through the agency of the beam or beams,- the 'rotating drum is caused to move downwardly, making a complete vertical cut at the face of the material. This procedure is then repeated and the mine entry is thereby advanced. At the position or positions where the drum is supported on one or more of the beams, the drum. cannot .carry cutting tools. Therefore, one or more trim chains are required to fill in the one or more portions of the drum not provided with cutting tools. By virtue of the construction of such mining machines, it will be understood that the trim chains have to be of considerable width. As a consequence, such trim chains usually carry a plurality of cutting tools oriented in staggeredrows extending the width of the chain.

Heretofore, such trim chains comprised a plurality of chain blocks joined together by two or more connecting links. Each chain block was as wide as the chain width requiredand carried at least one cutting tool in a predetermined position. along the chain width. Thus, for each cutting tool position along the chain width, there had to be a separate type of chain: block configured to mount the cutting tool in that position. Thus, for purposes of an exemplary showing, if a given chain was adapted to carry cutting tools in five different positions across the width of the chain, there would have to be five difi'erent chain blocks used to make up the chain. Each chainwould therefore be made up of a plurality of .each of the five chain block types joined together by. connecting links so that the cutting tools could be arranged in the desired patternsacross the width of the chain and throughout the chain length.

While such chains performed well in the field, they .required the mine owner to carry a large inventory of difierent and expensive chain blocks, for purposes of replacement and repair.

In addition, if the mine owner had several different non-oscillating drum-type mining machines, each requiring trim chains of different widths, he was required to maintain an inventory of sets of chain blocks for each type of machine.

The present invention isdirected to a chain construction whereby a trim chain of the type described may be made up in any suitable width and length and having any desired cutting tool arrangement thereon, and yet requiring the stocking of only a minimum number of standardized parts as will be described hereinafter.

.dimensions. The chain will be made up of a plurality of transverse rows of these elements in side-by-side relationship, each .intermediate row having one less element than the row ahead and behind.it.lThe number of elements in each row may be varied so as to provide a chain of any desired width. The chain block elements. and connecting link elements may be interchanged soas to. enable the chain tocarry cutting tools in any desired pattern or arrangement. The various elements are held together by connecting pins'ofv appropriate length. according to the width of the. chain to be produced.

' Where desired, a pair of simple spacer elements maybe substituted for. a connecting :link, for purposes of economy. The type of .cuttingtool. carried bythe'chain block does not con- .stitute a'limitation onthe present invention.

In another embodiment ofthev present invention," the-chain can serve as a tread for a self-propelled vehicle. When'soused,

..--all of the link elements comprising the chain may be identical 25 BRIEF DESCRIPTION OF THE DRAWINGS FIG. I is a semi-diagrammatic front elevational view of a typical non-oscillating drum-type mining machine.

- FIG. 2'is an isometric view of a connecting link of a chain of the present invention.

FIGJ3 is an isometric view of a chain block of a chain of the present invention.

FIGS.-4 and 5 are perspective views of a cutting tool and retaining means to be usedwith the chain block of FIG. 3.

FIG; '6 is an isometric view of a spacer for use in a chain of the present invention.

FIG? 7 is 'an isometric exploded view of a connecting pin, .nuts and locking pins to be .used in a chain of the present invention.

FIG. 8 is an isometric view illustrating one embodiment of the chain of the present invention.

FIG.-9 is a perspective view of another type of connecting pm.

FIG. 10 is an isometric view of a connecting link to be used with the connecting pin of FIG. 9.

'FIG. 11 is a side elevational view of another type of chain block to beused in the chain of the present invention.

FIG. 12 is a side elevational view of a link. element to be used in the chain of the present invention, when the chain is to serve as a tread.

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a semi-diagrammatic front view of a non-oscillating drum-type mining machine, generally indicated at l. The

machine has a self-propelled body portion2 with centrally located conveyor means 3. A pair of spaced, movable beams'4 and 5 support a rotatable drum 6 having two helical rows of cutting tools 6a and 6b. Appropriate drive means for the drum is located in association with or between the beams. The

FIG. 2 illustrates a typical connecting link used in the chain of the present invention. The connecting link 9 comprises an elongated member having perforations 10 and 11 at each end. The perforations 10 and 11 are adapted to receive a connecting pin, as will be described hereinafter. The bottom surface of the connecting link may be arcuately relieved as at 12, to aid it in passing over a curved surface. The upper surface of the connecting link may be notched as at 13 both to conserve material and for reasons hereinafter set forth.

FIG. 3 illustrates a chain block for use in the chain of the present invention. The chain block 14 has a body portion 15 which is substantially identical to the connecting link 9 of FIG. 2. The body portion 15 has perforations 16 and 17, identical to perforations 10 and 11 of the connecting link 9. The bottom surface of the chain block may be relieved as at 18, in a manner identical to the relief 12 of the connecting link 9. Finally, the body portion 15 has a notch 19 identical to the notch 13 in the connecting link 9. The chain block 14 has affixed thereto a cutting tool carrying element 20. While the configuration of the element 20 does not constitute a limitation on the present invention, FIG. 3 illustrates it in one of its most economic and easily manufactured forms. In the exemplary embodiment, the element 20 is shown as being made of round stock provided with a central perforation 21 and an external flat 22. The element 20 has a forward face 23 and a rearward face 24. The element 20 is attached to the body portion 15 of the chain block by welding or otherwise affixing the flat 22 to the portion 19a of the notch 19.

It will be understood by one skilled in the art that the element 20 could constitute an integral part of the chain block 14. However, when it is made as a separate part permanently affixed to the body portion 15, this enables the manufacture of a single element which can serve either as a connecting link 9 or the body portion 15 ofa chain block 14.

It will be evident from FIG. 3 that the cutting tool carrying element 20 is affixed to be body portion 15 in such a way that its rearward surface 24 is spaced from the portion 19b of the notch 19. The perforation 21 serves as a shank receiving perforation for a cutting tool and the portion 19b of the notch 19 serves as a rear abutment for the cutting tool.

While the type of cutting tool used in the chain of the present invention does not constitute a limitation thereon, the exemplary embodiment shown in FIG. 3 illustrates a mounting means of the general type taught in U.S. Letters'Pat. Nos, 3,397,012 and 3,397,013 for cutting tools of the type taught in the same patents. For purposes of an exemplary showing, FIGS. 4 and 5 respectively illustrate a typical cutting tool and a retaining means therefor. The cutting tool, generally indicated at-25 comprises an elongated shank 26 terminating at one end in a hard cutting tip 27 and terminating at the other end in an abutment surface 28 adapted to cooperate with the portion 19b of the notch 19 in FIG. 3. The shank 26 has an annular notch 29 therein which extends in part at least beyond the rearward surface 24 of the cutting tool carrying element 20 and which is adapted to receive the split metal retaining ring 30 of FIG. 5. The external diameter of the ring 30 is slightly greater than the diameter of the shank receiving perforation 21 (FIG. 3) so that the ring 30 will prevent loss of the bit 25 from the shank receiving perforation 21.

It will be understood by one skilled in the an that the surface 19b of the notch 19 and the abutment surface 28 of the cutter bit may be so configured as to provide a male-female fit, as taught in the above mentioned U.S. Pat. No. 3,397,013. Similarly, resilient means may be provided in association with the surface 19b of the notch 19 to provide a resilient mounting for the cutter bit, as taught in the copending application filed Dec. 15, 1969, Ser. No. 885,255 entitled RESILIENT MOUNTING FOR CUTTING TOOLS OF MINING MACHINES AND THE LIKE, in the name of the same inventor.

FIG. 6 illustrates a spacer, a pair of which may be substituted for a connecting link, as will be described hereinafter. The spacer 31 comprises simply a cylindrical element having the same width as the chain block of FIG. 3 or the connecting link of FIG. 2. The spacer has a central perforation 32 equivalent to the perforations 10 and 11 of the connecting link or the perforations 16 and 17 of the chain block.

FIG. 7 is an exploded, isometric view of one embodiment of a connecting pin whereby the connecting links and chain blocks making up the chain of the present invention may be joined together. In this embodiment, the connecting pin comprises an elongated cylindrical member 32 of such diameter as to be freely rotatable in any of the perforations 10-11, 16-17 or 32 of FIGS. 2, 3 and 6, respectively. The cylindrical element 32 is threaded at both ends, as at 33 and 34. The connecting pin 32 is of such length that the threaded ends 33 and 34 will extend beyond the width of the trim chain. A pair of internally threaded nuts 35 and 36 are adapted to be received on the threaded ends 33 and 34, respectively. Finally, the threaded ends 33 and 34 may be provided with transverse perforations 33a and 34a, respectively. Similarly, the nuts 35 and 36 may be provided with transverse perforations 35a and 36a, respectively. When the nuts 35 and 36 are threaded onto their respective ends of the pin 32, the perforations 35a may be rendered coaxial with the perforation 33a and similarly the perforations 36a may be rendered coaxial with the perforation 34a so that roll pins 35b and 36b, or the like, may be used to lock the nuts firmly in place on the connecting pin.

It will be understood that roll pins 35b and 36b may be replaced by solid pins or any other suitable locking means, where desired. It will be further understood that either the perforations 33a and 34a in the connecting pin 32 or perforations 35a and 36a in nuts 35 and 36 may be enlarged to aid in the installation of locking pins 35b and 36b.

FIG. 8 is an isometric view of an assembled chain in accordance with the present invention. Like parts have been given like index numerals. In the particular embodiment shown, the chain is five elements wide and provides a plurality of staggered rows of five cutting tools across the width of the chain. In the portion of the chain shown in FIG. 8, eight chain blocks are illustrated. All of the remaining elements may be connecting links of the type shown in FIG. 2. However, where desired, connecting links may be replaced by pairs of spacers 31, as illustrated.

It will be evident to one skilled in the art from FIG. 8 that any desired pattern or arrangement of cutting tools may be achieved in the chain of the present invention, simply by the appropriate interchange of chain blocks 14 and connecting links 9. The chain may be made wider or narrower by the width-wise addition or removal of chain blocks and connecting links. The mine owner need only stock chain blocks, connecting links and connecting pins of appropriate length. It will be noted that there is only one type of chain block used throughout the chain. Where desired, the mine owner may also stock spacers, for purposes of economy, but connecting links may be used in their stead, as indicated above. At a given time, should a mine owners stock of connecting links be low, it is possible to substitute a chain block for a connecting link.

In the embodiment shown in FIG. 8, it will be noted that the connecting pins 32 and nuts 35 and 36 provide means beyond the edge of the chain engageable by sprocket wheels or the like. Alternatively, depending upon the mining machine in question, the teeth of a sprocket wheel may extend into the space 37 between the outermost connecting links or chain blocks and contact the links or blocks themselves to drive the chain. Similarly, sprocket wheels may be so located that their teeth enter corresponding spaces 37a in the central portion of the chain and contact adjacent links or blocks to drive the chain.

When this is the case, any suitable and well known means may be employed to maintain the connecting pins in place. For example, the connecting pins need not extend beyond the outside surfaces of the outermost connecting links or chain blocks, but may be held in place by spring means or clips similar to those well known in the art with respect to maintaining pintles in place in cutter chains or the like. On the other hand, the connecting pins may extend beyond the outside surfaces of the outermost links or chain blocks and be held in place by roll pins extending through the projecting portions of the connecting pins. Alternatively, the projecting portions of the connecting pins may be provided with annular grooves adapted to receive C-shaped clips or the like.

An alternative form of connecting pin is illustrated at 38 in FIG. 9. The connecting pin 38 has an elongated shank portion 39 similar to that of the pin 32 of FIG. 7. In this instance, however, the connecting pin 38 is headed at both ends with integral, non-removable heads 40 and 41. FIG. illustrates a connecting link 42 to be used with the connecting pin of FIG. 9. The connecting link 42 is in every way identical to the connecting link of FIG. 2 with the exception that perforations 10a and 110 have enlarged portions 10b and 11b. It will be understood by one skilled in the art that the chain blocks can be provided with similarly configured perforations.

In the typical mining machine of the type described, provision is made whereby the chain may be rendered slack for purposes of replacement or repair. When the chain is in slack position and the connecting links and chain blocks are provided with perforations of the type shown in FIG. 10, the headed portions 40 or 41 of connecting pins of the type shown in FIG. 9 can pass through the enlarged portions 10b or 11b of the perforations 10a or lla. When the chain is returned to its normal tightened position, the shank portion 39 of the connecting pins will enter the smaller portions of the perforations 10a and 11a and the headed portions 40 and 41 of the connecting pins will prevent their loss or removal.

The connecting pins illustrated in FIGS. 7 and 9 have the advantage that they are freely rotatable in the perforations in the connecting links and chain blocks. Thus, these connecting pins will be subject to even wear about their peripheries.

As indicated above, the type of bit mounted in the chain blocks does not constitute a limitation on the present invention. The precise configuration of the chain blocks will vary, depending upon the type of bit used. For purposes of the present invention, however, it is only important that the chain blocks have the same length and width as the connecting links.

It would be within the scope of the invention to provide chain blocks so configured as to accept cutter bits of the types taught in U.S. Letters Pat. No. 3,622,206. Alternatively, the chain blocks could be configured to accept bits of the type taught in U.S. Letters Pat. No. 3,114,537. This is illustrated, by way of example, in FIG. 11.

FIG. 11 shows a chain block 43 which could be substituted for the chain blocks 14 in FIG. 8. The chain block 43 is similar to that of FIG. 3 in that it is provided with perforations 44 and 45 for the receipt of connecting pins. The bottom surface may be arcuately relieved, as at 46, in the same manner taught with respect to the block in FIG. 3. In this instance, however, the chain block is provided with a shank receiving perforation 47 passing downwardly therethrough, and an intersecting transverse perforation 48 containing a resilient retaining means 49.

FIG. 11 shows a typical bit of the type taught in the above mentioned U.S. Letters Pat. No. 3,114,537. The bit 50 has a head portion 51 with a hard cutting tip 52 and a shank portion 53 of rectangular cross section. The shank 53 is receivable in the shank receiving perforation 47. The rear edge of the shank 53 has a notch 54 therein adapted to coact with the resilient retaining means 49. The head portion 51 of the bit has a gauge determining abutment surface 55 adapted to cooperate with the upper surface 56 of the chain block.

Modifications may be made in the invention without departing from the spirit of it. For example, the chain of the present invention may be adapted for use as a tread for a selfpropelled mining machine or the like. In such an instance, all of the link elements may be identical and may be of the general type illustrated in FIG. 12.

The link element 57 of FIG. 12 is similar to the connecting link of FIG. 2, having connecting pin perforations 58 and 59. If desired, the link element may be relieved, as shown in dotted lines at 60, for purposes of economy.

The link element 57 differs from the connecting link of FIG. 2 primarily in that the bottom surface 61 is not relieved and the ends of the link element are extended as at 62 and 63.

The extensions 62 and 63 serve two purposes. First of all, they ensure that each link will present a maximum surface to the ground over which it travels. Secondly, each extension 62 and 63 forms a notch, generally indicated at 620 and 63a. These notches, in conjunction with similar notches on adjacent link members will form pockets for the receipt of the teeth of driving sprockets or thelike. Additionally, it is within the scope of the invention to provide the bottom surface 61 with cleats or other configurations (not shown) to ensure greater traction.

When the chain of the present invention is to be used as a tread, it may include a plurality of modified links in addition to the standard link elements, to achieve various desired effects. For example, certain of the links may have lugs or additional extensions thereon to cooperate with guide means on the vehicle to insure proper alignment of the tread.

Additional modifications may be made without departing from the spirit of the invention. For example, the chain of the present invention may be adapted for use on a continuous mining machine of the general type set forth in U.S. Letters Pat. No. 2,926,896. In such an application, the chain of the present invention would present the same advantages as outlined above with respect to its application as a trim chain. In addition, the mining machine itself could be simplified in a number of respects, including the elimination of a number of guide means and the like, heretofore required when individual chains were used.

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. A continuous chain for a mining machine or the like comprising a plurality of elongated link elements, some of said link elements comprising connecting links, some of said link elements comprising cutting tool carrying links, all of said link elements being of equal length and width, each of said link elements having a transverse perforation at each end, said link elements being arranged in first groups having the same number of link elements and second groups having the same number of link elements, the number of link elements in a first group being one greater than the number of link elements in a second group, said first and second groups of link elements being arranged alternately one behind the other with the ends of the link elements of adjacent groups being in interdigitated relationship and with said perforations therein in coaxial relationship, connecting pins passing through said coaxial perforations to pivotally join said interdigitated ends, said connecting links and said cutting tool carrying links being interchangeable within and between said first and second groups whereby said cutting tool carrying links may be arranged along the length of said chain and transversely thereof in any desired pattern.

2. The structure claimed in claim I wherein said connecting pins are freely rotatable in their respective coaxial perforations in said link elements, and means for retaining said connecting pins in their respective coaxial perforations.

3. The structure claimed in claim 1 including cylindrical spacers having axial perforations therein, said spacers having a width equal to the width of said link elements, pairs of said spacers being substituted for selected ones of said link elements, the spacers of each pair being located on adjacent ones of said connecting pins in positions which would otherwise be occupied by a single link element, all of said first and second groups having at least two link elements therein.

4. The structure claimed in claim 1 wherein said connecting pins each comprise an elongated cylindrical body terminating in enlarged ends, each of said transverse perforations in said link elements comprising a pair of intersecting holes having parallel axes so that each of said perforations constitutes a first portion with a diameter slightly larger than the diameter of said body of said connecting pins and smaller than the diameter of said enlarged ends and a second portion partially intersecting said first portion and having a diameter slightly larger than said ends of said connecting pins, said perforations being so configured that when said chain is slack connecting pins may be passed through the second portions of the perforations of said adjacent groups of links in interdigitated relationship, the body of said connecting pins entering and being freely rotatable in the first portion of said perforations when said chain is taut, said enlarged ends of said connecting pins preventing loss of said connecting pins when said chain is taut.

5. The structure claimed in claim 1 wherein said connecting pins each comprise an elongated cylindrical body portion terminating in enlarged end members, means to prevent rotation of said end members with respect to said body portion, at least one of said enlarged end members being removably affixed to said body portion.

6. The structure claimed in claim 1 wherein all of said connecting links are identical and all of said cutting tool carrying links are identical.

7. The structure claimed in claim 1 wherein each of said cutting tool carrying links is intended to carry a rotatable cutting tool of the type comprising an elongated shank with a cutting tip at one end and an abutment surface at the other end, each of said cutting tool carrying links comprising an elongated body having said transverse perforations at each end thereof, said body having a first upper portion with a perforation of circular cross section therethrough adapted to receive said shank of said cutting tool such that said shank is rotatable therein, said body have a second portion spaced rearwardly of said first portion and presenting an abutment surface for said abutment end of said cutting tool shank.

8. The structure claimed in claim 1 wherein each of said cutting tool carrying links is intended to carry a rotatable cutting tool of the type comprising an elongated shank with a cutting tip at one end and an abutment surface at the other end, each of said cutting tool carrying links comprising an elongated body having said transverse perforations at each end thereof, said body having an upper portion with a V- shaped notch therein, said V-shaped notch forming first and second angularly related surfaces on said upper portion of said body, a cutting tool mounting means affixed to said first surface and spaced from said second surface, said cutting tool mounting means having a perforation of circular cross section therethrough adapted to receive said shank of said cutting tool such that said shank is rotatable therein, said second surface comprising an abutment surface for said abutment end of said cutting tool shank.

9. The structure claimed in claim 1 wherein at least selected ones of said pins are of greater length than the total width of the respective interdigitated link element ends they join, the end portions of said selected pins extending beyond the link element ends they join and being engagable by toothed sprocket means.

10. The structure claimed in claim 1 wherein said chain is adapted to pass over one or more toothed sprocket means chosen from the class consisting of driving, driven and idler sprockets, any of said link elements being contactable by the teeth of said sprocket means depending upon the relative position of said sprocket means with respect to said chain transversely thereof.

11. The structure claimed in claim 1 wherein said connecting pins each comprise an elongated cylindrical body portion terminating in enlarged end members, at least one of said enlarged end members being removably affixed to said body portion.

12. The structure claimed in claim 11 wherein said chain is adapted to pass about one or more toothed sprocket means chosen from the class consisting of driving, driven and idler sprockets, at least one of said end members of said selected ones of said pins being contactable by said sprocket means.

13. The structure claimed in claim 1 wherein each of said cutting tool carrying links comprises an elongated body having said transverse perforations at each end thereof, said body having an additional perforation therein adapted to receive the shank of a cutting tool.

14. The structure claimed in claim 13 wherein said shank receiving perforation is of rectangular cross section.

15. The structure claimed in claim 13 wherein said shank receiving perforation is of circular cross section.

16. The structure claimed in claim 1 wherein each of said tool carrying links has a shank receiving perforation of circular cross section adapted to receive the shank of a cutting tool of the type comprising a shank of circular cross section terminating at one end in a cutting tip, said shank receiving perforation being of such diameter that said cutting tool shank is freely rotatable therein.

17. The structure claimed in claim 13 wherein said shank receiving perforation has an abutment surface in association therewith and is adapted to receive the shank of a cutting tool of the type comprising a shank of circular cross section terminating at one end in a cutting tip, said cutting tool having an abutment surface thereon, said shank receiving perforation being of such diameter that said cutting tool shank is freely rotatable therein, said abutment surface in association with said shank receiving perforation and said cutting tool abutment surface being adapted to be in abutting relationship.

18. A continuous chain for a mining machine or the like comprising a plurality of elongated link elements, some of said link elements comprising connecting links, some of said link elements comprising cutting tool carrying links, each of said link elements having a transverse perforation at each end, said link elements being arranged in groups with the transverse perforations of the link elements of each group being in coaxial relationship, said groups of link elements being arranged one behind the other with the ends of the link elements of adjacent groups being in interdigitated relationship, the transverse perforations in said interdigitated ends being in coaxial relationship, connecting pins passing through said coaxial perforations to pivotally join said interdigitated ends, said connecting links and said cutting tool carrying links being interchangeable within and between said groups whereby said cutting tool carrying links may be arranged along the length of said chain and transversely thereof in any desired pattern.

19. The structure claimed in claim 18 including cylindrical spacers having axial perforations therein, said spacers being substituted for selected ones of said link elements. 

1. A continuous chain for a mining machine or the like comprising a plurality of elongated link elements, some of said link elements comprising connecting links, some of said link elements comprising cutting tool carrying links, all of said link elements being of equal length and width, each of said link elements having a transverse perforation at each end, said link elements being arranged in first groups having the same number of link elements and second groups having the same number of link elements, the number of link elements in a first group being one greater than the number of link elements in a second group, said first and second groups of link elements being arranged alternately one behind the other with the ends of the link elements of adjacent groups being in interdigitated relationship and with said perforations therein in coaxial relationship, connecting pins passing through said coaxial perforations to pivotally join said interdigitated ends, said connecting links and said cutting tool carrying links being interchangeable within and between said first and second groups whereby said cutting tool carrying links may be arranged along the length of said chain and transversely thereof in any desired pattern.
 2. The structure claimed in claim 1 wherein said connecting pins are freely rotatable in their respective coaxial perforations in said link elements, and means for retaining said connecting pins in their respective coaxial perforations.
 3. The structure claimed in claim 1 including cylindrical spacers having axial perforations therein, said spacers having a width equal to the width of said link elements, pairs of said spacers being substituted for selected ones of said link elements, the spacers of each pair being located on adjacent ones of said connecting pins in positions which would otherwise be occupied by a single link element, all of said first and second groups having at least two link elements therein.
 4. The structure claimed in claim 1 wherein said connecting pins each comprise an elongated cylindrical body terminating in enlarged ends, each of said transverse perforations in said link elements comprising a pair of intersecting holes having parallel axes so that each of said perforations constitutes a first portion with a diameter slightly larger than the diameter of said body of said connecting pins and smaller than the diameter of said enlarged ends and a second portion partially intersecting said first portion and having a diameter slightly larger than said ends of said connecting pins, said perforations being so configured that when said chain is slack connecting pins may be passed through the second portions of the perforations of said adjacent groups of links in interdigitated relationship, the body of said connecting pins entering and being freely rotatable in the first portion of said perforations when said chain is taut, said enlarged ends of said connecting pins preventing loss of said connecting pins when said chain is taut.
 5. The structure claimed in claim 1 wherein said connecting pins each comprise an elongated cylindrical body portion terminating in enlarged end members, means to prevent rotation of said end members with respect to said body portion, at least one of said enlarged end members being removably affixed to said body portion.
 6. The structure claimed in claim 1 wherein all of said connecting links are identical and all of said cutting tool carrying links are identical.
 7. The structure claimed in claim 1 wherein each of said cutting tool carrying links is intended to carry a rotatable cutting tool of the type comprising an elongated shank with a cutting tip at one end and an abutment surface at the other end, each of said cutting tool carrying links comprising an elongated body havIng said transverse perforations at each end thereof, said body having a first upper portion with a perforation of circular cross section therethrough adapted to receive said shank of said cutting tool such that said shank is rotatable therein, said body have a second portion spaced rearwardly of said first portion and presenting an abutment surface for said abutment end of said cutting tool shank.
 8. The structure claimed in claim 1 wherein each of said cutting tool carrying links is intended to carry a rotatable cutting tool of the type comprising an elongated shank with a cutting tip at one end and an abutment surface at the other end, each of said cutting tool carrying links comprising an elongated body having said transverse perforations at each end thereof, said body having an upper portion with a V-shaped notch therein, said V-shaped notch forming first and second angularly related surfaces on said upper portion of said body, a cutting tool mounting means affixed to said first surface and spaced from said second surface, said cutting tool mounting means having a perforation of circular cross section therethrough adapted to receive said shank of said cutting tool such that said shank is rotatable therein, said second surface comprising an abutment surface for said abutment end of said cutting tool shank.
 9. The structure claimed in claim 1 wherein at least selected ones of said pins are of greater length than the total width of the respective interdigitated link element ends they join, the end portions of said selected pins extending beyond the link element ends they join and being engagable by toothed sprocket means.
 10. The structure claimed in claim 1 wherein said chain is adapted to pass over one or more toothed sprocket means chosen from the class consisting of driving, driven and idler sprockets, any of said link elements being contactable by the teeth of said sprocket means depending upon the relative position of said sprocket means with respect to said chain transversely thereof.
 11. The structure claimed in claim 1 wherein said connecting pins each comprise an elongated cylindrical body portion terminating in enlarged end members, at least one of said enlarged end members being removably affixed to said body portion.
 12. The structure claimed in claim 11 wherein said chain is adapted to pass about one or more toothed sprocket means chosen from the class consisting of driving, driven and idler sprockets, at least one of said end members of said selected ones of said pins being contactable by said sprocket means.
 13. The structure claimed in claim 1 wherein each of said cutting tool carrying links comprises an elongated body having said transverse perforations at each end thereof, said body having an additional perforation therein adapted to receive the shank of a cutting tool.
 14. The structure claimed in claim 13 wherein said shank receiving perforation is of rectangular cross section.
 15. The structure claimed in claim 13 wherein said shank receiving perforation is of circular cross section.
 16. The structure claimed in claim 1 wherein each of said tool carrying links has a shank receiving perforation of circular cross section adapted to receive the shank of a cutting tool of the type comprising a shank of circular cross section terminating at one end in a cutting tip, said shank receiving perforation being of such diameter that said cutting tool shank is freely rotatable therein.
 17. The structure claimed in claim 13 wherein said shank receiving perforation has an abutment surface in association therewith and is adapted to receive the shank of a cutting tool of the type comprising a shank of circular cross section terminating at one end in a cutting tip, said cutting tool having an abutment surface thereon, said shank receiving perforation being of such diameter that said cutting tool shank is freely rotatable therein, said abutment surface in association with said shank receiving perforation and said cutting tool abutment surface being adapted To be in abutting relationship.
 18. A continuous chain for a mining machine or the like comprising a plurality of elongated link elements, some of said link elements comprising connecting links, some of said link elements comprising cutting tool carrying links, each of said link elements having a transverse perforation at each end, said link elements being arranged in groups with the transverse perforations of the link elements of each group being in coaxial relationship, said groups of link elements being arranged one behind the other with the ends of the link elements of adjacent groups being in interdigitated relationship, the transverse perforations in said interdigitated ends being in coaxial relationship, connecting pins passing through said coaxial perforations to pivotally join said interdigitated ends, said connecting links and said cutting tool carrying links being interchangeable within and between said groups whereby said cutting tool carrying links may be arranged along the length of said chain and transversely thereof in any desired pattern.
 19. The structure claimed in claim 18 including cylindrical spacers having axial perforations therein, said spacers being substituted for selected ones of said link elements. 